The detection of volatile organic compounds (VOCs) and humidity has many commercial, public, and residential applications due to environmental and safety concerns. One useful sensor type is a capacitive sensor in which a sorbent material is disposed between two electrodes. Typically, at least one of the electrodes is porous or otherwise permeable by the analyte vapor to be measured. Examples of sorbent materials used in these types of sensors include so-called Polymers of Intrinsic Microporosity (PIMs, for VOC measurement) and sulfonated fluoropolymers (for humidity measurement).
Conventionally, the electrodes are metal (e.g., gold) that are typically vapor-deposited, requiring a well-controlled vapor deposition process to produce electrodes with consistent porosity.